Settings

Now showing1 - 4 of 4
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Publication, Access status: without files ,
    In silico studies of fluid flow, digestion of food and drug dissolution in human stomach
    (Springer, 2025-01-06)
    Li, Changyong
    ;
    Xiao, Jie
    ;
    Chen Xiao Dong
    ;
    Jin, Yan
    This review article explores the significant role of in silico simulations as complements to in vivo and in vitro experiments, particularly in enhancing our understanding of gastric flow, digestion, and drug dissolution. By synthesizing decades of research on numerical stomach models, this paper highlights the profound impact computational fluid dynamics (CFD) and other simulation techniques have on elucidating the influence of gastric motility and the physical properties of stomach contents on nutrient absorption and drug release. These simulation studies provide more detailed information for us to advance our understanding of drug delivery in stomach and to support the formulation of functional foods tailored for specific metabolic health requirements. Additionally, these models offer valuable forecasts that aid in refining surgical methods and therapeutic approaches, especially for managing conditions such as gastroparesis. By advancing our fundamental understanding of digestive mechanisms, in silico studies contribute significantly to the development of innovative treatments and the enhanced management of gastrointestinal disorders, underscoring the transformative potential of computational tools in nutritional science and biomedicine.
    Publicationtype: Journal Article
      29
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Publication, Access status: without files ,
    Impact of reduced gravity on food mixing and emptying in human stomach : a numerical simulation study
    (American Institute of Physics (AIP), 2024-06-14)
    Li, Changyong
    ;
    Chen, Xiao Dong
    ;
    Xiao, Jie
    ;
    Deng, Renpan
    ;
    Jin, Yan
    Gravitational conditions in space diverge significantly from those experienced on Earth, and these alterations may have significant effects on gastric digestion, ultimately affecting the health of astronauts. To understand these effects, the behavior of mixing and emptying in the human stomach under both reduced and normal gravity is investigated numerically. The solver utilized in this study is developed based on the open-source toolbox OpenFOAM. The gastric contents consist of water and a soluble food bolus characterized by a density of 1100 kg m−3, viscosity of 10−5 m2 s−1, and diffusivity of 3.09 × 10−9 m2 s−1. The effects of gravity magnitude, initial food bolus location, and terminal antral contractions (TACs) are studied. The numerical results demonstrate that the food retention rate can be increased by up to ∼20% in the initial 6 min as normal gravity is reduced to zero gravity. The numerical results support that gravity favors the emptying of the food through the pylorus. The distributions of food concentrations and pH are also significantly influenced by the gravity condition. Under zero gravity conditions, food in the distal stomach is quickly emptied due to the strong flow dynamics in the antrum. A delay of approximately 6 min is observed when the food bolus is initially located in the proximal stomach. TACs efficiently enhance the emptying and mixing of the food in the distal stomach, while their effects on the proximal stomach are marginal.
    Publicationtype: Journal Article
      68
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Publication, Access status: without files ,
    Digestion of meat proteins in a human-stomach: A CFD simulation study
    (2023-01)
    Li, Changyong
    ;
    Jin, Yan
    Understanding gastric digestion mechanisms is important for the design of functional foods. In this study, we have investigated the meat-protein digestion in human-stomach by using a CFD method. The gastric motility is modeled with a dynamic mesh. The disintegration of large food particles in an acidic environment is simulated using a reaction-diffusion-convection model. A food matrix is used to model the large food-particles. The numerical results show that the digestion and emptying become faster when the meat is treated at a higher temperature. The digestion rate is reduced considerably when the gastric motility or the H+ secretion is weakened due to a stomach disorder. TACs stimulate backflows which enhance the transport of enzymes and H+, thereby accelerating the digestion process. Due to the flow resistance by the food matrix made of large food particles, liquid gastric contents are emptied in a pathway close to the stomach inner-surface. Large food-particles are mainly disintegrated in the region next to the stomach inner-surface. Therefore, the characteristic length scale of species transport (for enzymes or H+) should be the size of food matrix, instead of the size of large food-particles.
    Publicationtype: Journal Article
      45
  • Some of the metrics are blocked by your 
    consent settings
    Item type:Publication, Access status: with files ,
    Effects of end-walls on flows in a highly loaded compressor cascade with double-circular-arc blades
    (American Institute of Physics (AIP), 2022-05-19)
    Jin, Yan
    ;
    Li, Changyong
    ;
    Du, Juan
    ;
    Zhang, Hongwu
    A numerical study is carried out to understand the flows in a highly loaded compressor cascade made of double-circular-arc blades, which were measured by Zierke and Deutsch in the late 1980s. A two-dimensional (2D) cascade with periodic boundary conditions in both pitch-wise and span-wise directions and a three-dimensional (3D) cascade with two end-walls that are far away from each other are accounted for in the study. For the incidence angle α = - 8.5 °, the numerical results of the 2D-cascade flow are in excellent accordance with the experimental data. This not only validates the numerical method used in the study but also suggests that a 2D and periodic flow was successfully generated in the experiment for this incidence angle. However, the numerical results of 2D-cascade flows for α = - 1.5 ° and 5 ° deviate from the experiment considerably because the strong effects of the end-walls on the wake are neglected in the simulation. By contrast, the simulation of 3D-cascade flows predicts an accurate pressure coefficient at the blade surface, the pressure increase coefficient, and the total pressure loss coefficient for all three incidence angles. This means that, to generate experimental data for validating numerical simulation, it is important to consider the effect of end-walls when the incidence angle is large. The numerical results also show that, for 2D-cascade flows with a low inlet turbulence intensity, the laminar-turbulent transition on the pressure surface is determined by the interaction of the Klebanoff distortions and T-S waves. The Klebanoff distortions are also clearly identified on the suction surface for α = - 8.5 °. The end-walls induce span-wise elongated disturbances, which suppress the stream-wise disturbances. The transition in 3D-cascade flows generally follows the mechanism of natural transition.
    Publicationtype: Journal Article
    Scopus© Citations 4  52  438